I play the piano, but don't have any idea how to play the organ or the keyboard. What 's the dfference? I notice that the foot pedals of the organ is configured like the keyboard of the piano and perhaps the left foot presses the key or note acoording to the notation. But how does one play a keyboard? any beginning books?

When you say keyboard, I'm assuming you're referring to digital or electronic keyboards or pianos. The layout of the keyboard on these are going to be just like the piano, so you should be able to play them just fine. Depending on the keyboard, it may or may not have a full 88 keys like the acoutic piano. I'm not an organist either. You'll find the organ has a multi tiered key layout. I've tried playing one of these and it's not as easy as it might look. And you're right about the foot pedals. It is configured like the piano keyboard, and organ music (I think) has foot pedal markings. I believe you can use either or both feet. Perhaps an organist might shed a more descriptive and/or accurate picture.